Insulin and other injectable medications are commonly given with drug delivery pens, whereby a disposable pen needle is attached to facilitate drug container access and allow fluid egress from the container through the needle into the patient.
As technology and competition advance, driving the desire for shorter, thinner, less painful, and more efficacious injections, the design of the pen needle and parts thereof becomes more and more important. Designs need to proactively address ergonomically improving injection technique, injection depth control and accuracy, the ability to be safely used and transported to disposal, and protection against misuse while maintaining the ability to be economically manufactured on a mass production scale.
Drug delivery devices, such as the exemplary drug delivery pen 100 shown in FIGS. 1 and 2, can be designed for subcutaneous, as well as intradermal, injections and typically comprise a dose knob/button 24, an outer sleeve 13, and a cap 21. The dose knob/button 24 allows a user to set the dosage of medication to be injected. The outer sleeve 13 is gripped by the user when injecting medication. The cap 21 is used by the user to securely hold the drug delivery pen 100 in a shirt pocket, purse or other suitable location and provide cover/protection from accidental needle injury.
FIG. 2 is an exploded view of the drug delivery pen 100 of FIG. 1. The dose knob/button 24 has a dual purpose and is used both to set the dosage of the medication to be injected and to inject the dosed medicament via the leadscrew 7 and stopper 15 through the medicament cartridge 12, which is attached to the drug delivery pen through a lower housing 17. In standard drug delivery pens, the dosing and delivery mechanisms are all found within the outer sleeve 13 and are not described in greater detail here as they are understood by those knowledgeable of the prior art. The distal movement of the plunger or stopper 15 within the medicament cartridge 12 causes medication to be forced into the steel needle 11 of the hub 20. The medicament cartridge 12 is sealed by septum 16, which is punctured by a septum penetrating needle cannula 18 located within the hub 20. The hub 20 is preferably screwed onto the lower housing 17, although other attachment means can be used, such as attaching to the cartridge. To protect a user, or anyone who handles the pen injection device 100, an outer cover 69, which attaches to the hub 20, covers the hub. An inner shield 59 covers the patient needle 11 within the outer cover 69. The inner shield 59 can be secured to the hub 20 to cover the patient needle by any suitable means, such as an interference fit or a snap fit. The outer cover 69 and the inner shield 59 are removed prior to use. The cap 21 fits snugly against outer sleeve 13 to allow a user to securely carry the drug delivery pen 100.
The medicament cartridge 12 is typically a glass tube sealed at one end with the septum 16 and sealed at the other end with the stopper 15. The septum 16 is pierceable by a septum penetrating cannula 18 in the hub 20, but does not move with respect to the medicament cartridge 12. The stopper 15 is axially displaceable within the medicament cartridge 12 while maintaining a fluid tight seal.
An exploded perspective view of a pen needle 2 of an exemplary drug delivery pen is shown in FIG. 3. The pen needle 2 includes the cover (outer shield) 69, an inner shield 59, a needle cannula 11, and a hub 20. A proximal end 310 of the needle cannula 11 is inserted into a center opening in the distal (patient) end 405 of the hub 20 until a predetermined length of the distal (patient) end 305 of the needle cannula 11 remains extended. The needle cannula 11 is secured by epoxy or adhesive in the distal end 405 of the hub 20 within the hub protrusion 420.
To protect users from injury and the needle cannula 11 from being damaged, the inner shield 59 covers the exposed portion of the needle cannula 11. The open proximal end 210 of the inner shield 59 is placed over the exposed portion of the needle cannula 11. The open proximal end 110 of the cover 69 envelops the inner shield 59, needle cannula 11, and hub 20.
The distal end 105 of the cover 69 is closed to prevent contamination and damage to the inner components of pen needle 2, and to prevent injury to anyone who may handle it prior to use. The proximal end 410 of the hub 20 is typically covered by a sanitary paper or foil cover (not shown) glued on an end 110 of the cover 69. The drug delivery pen is then ready for shipment to a user. When the user is ready to use the drug delivery pen, the sanitary cover (not shown) is removed from the cover 69, the hub 20 is screwed onto a lower housing 17 of a standard pen 100 (FIGS. 1 and 2), and the cover 69 and shield 59 are separately removed from the hub 20/cannula 11 subassembly by a pulling action. The distal end 205 of the inner shield 59 is closed to cover the distal end 305 of the needle cannula 11 after the cover 69 is removed to protect the user from an accidental needle stick. The inner shield 59 is then removed to access the needle cannula 11. Thus, two separate pulling actions are required to remove both the cover 69 and the shield 59.
Many existing replacement needle assemblies include an inner shield and outer cover. The outer cover typically has a sanitary paper or foil seal that a user must remove to connect the pen needle to the cartridge of the pen assembly. However, the sanitary seal can be difficult to grasp and remove from the pen needle. Furthermore, once the sanitary seal is removed from the pen needle, nothing prevents a used pen needle that has been removed from a pen cartridge from being reused. Moreover, without the sanitary seal, nothing prevents a user from being accidentally stuck by the uncovered needle. Thus, a need exists for a pen needle that is easy to use and prevents reuse.
Another existing problem with pen needles is that there is no means to easily determine whether the pen needle has been previously used. Thus, a need exists for a pen needle that locks the pen needle in an outer cover to prevent reuse. A need also exists for a pen needle that has a color indicator to indicate that the pen needle has been previously used.
Existing drug delivery pens are disclosed in U.S. Patent Application Publication Nos. 2006/0229562 to Marsh et al., published on Oct. 12, 2006, and 2007/0149924 to R. Marsh, published on Jun. 28, 2007, the entire contents of both of which are hereby incorporated by reference.
Accordingly, a need exists for a disposable pen needle having an outer cover including a cap having a tab that is connectable to the cap to prevent reuse of the pen needle and to provide an easy to use pen needle.